MYXOSTOMA MACROLEPIDOTUM. 123 



that name, and I am unable to distinguish it from typical macrolepidotum, 

 although the mouth is rather small, more like that of aureolum. 



I have identified certain specimens with Professor Cope's P. lachrymale 

 with a little doubt, as the points of differentiation which I notice are not 

 those emphasized by Professor Cope. The original types, which 1 believe 

 are now lost, were from the Neuse River in North Carolina. In describ- 

 ing this species, Professor Cope remarks, " This species is quite near the 

 la^t (P. erythrurw) and may at some future time be shown to be a local 

 variety of it, but in this case P. macrolepidotus must follow also." 



The synonyms of var. duquesnei may now be noticed. Of these, 

 the only one of importance is that of Catostomus erytkrurus Rafinesque, 

 recently recognized by Professor Cope as a species distinct from P. 

 duquesnii. 



The presence of ten ventral rays in duquesnii, as contrasted with nine 

 ventral rays in erytiirurus, is the chief point on which Professor Cope 

 relies to distinguish the two species. He also finds the mouth rather 

 more inferior in duquesnii, and the scales rather smaller, 7-48-7, instead 

 of 5-4l>-4. 



In regard to the number of ventral rays, my experience is that in every 

 species of the genus the normal number is nine, but that ten-rayed 

 individuals occur in the proportion of about one in twenty in any of the 

 species. I have seen specimens of duquesnii with nine rays on one side 

 and ten on the other. I have therefore discarded all consideration of 

 the number of ventral rays as a specific character. In regard to the 

 number of scales in the lateral line, the usual number in most of the 

 species is 43 to 44 5 but of every species in which I have been enabled 

 to examine a large series of individuals, I have found a range extend- 

 ing from 42 to 49. I have seen ten-rayed specimens of duquesnei with 

 large scales, and nine-rayed erythruri with small ones. Within the limit 

 of 42 to 50 I therefore do not consider the number of scales as a perma- 

 nent specific character. The greater prominence of the muzzle in duques- 

 nti, as observed by Professor Cope, is perhaps accidental or individual. 

 At all events, it is too uncertain a feature to base a species on. 



The Rutilus melanurus of Rafinesque is, as I have elsewhere shown, 

 probably a young Eed Horse, with a dusky-shaded dorsal and caudal, 

 which that acute, but superficial, observer mistook for a species of Dace. 



